Study Of Measurement On High-Frequency Electromagnetic Properties Of Graphene Films

With the increasing development of microwave technologyxmicrowave materials have been widely used in many fields, such as energy source, communications, bio-medicine and electronics. The rapid development of the science and technology requires that the circuits and components are moving in the direction of film and integration, and new electronic functional film materials are being widely developed and applied. The study and measurement of microwave electromagnetic properties of materials has become an important part of modern science and technology. Accurate measurement of the electromagnetic property of the film materials, has great signification in the engineering practice.Currently, the method of measuring the electromagnetic properties of materials at both home and abroad are transmission line method, the resonant cavity method, and four-probe method etc. A sample of particular size is required by both the transmission line method and resonant cavity method, but film sample with micro and nanostructures cannot be measured with them, also varying degrees of damage of the sample occurs with such method. Four-probe method cannot measure high frequency characteristic of the sample. Therefore, a measurement of measuring the micro-nanostructure material is urgently needed.In this paper, a highly efficient non-destructive measurement system of measuring high frequency electromagnetic properties of materials is built up, based on the principle of near-fielding scanning microwave microscope. Near-field scanning microwave microscope detects the offset of the resonance frequency and the quality factor when the sample moving toward the probe, then obtain the permittivity, conductivity or other physical parameter of the sample by the method of simulation model. Based on analyzing several different resonator structure, a h /4 coaxial resonator is chosen as the core of the system, and the size of the antenna and probe are determined, as the cavity is simulated by the HFSS software. Then the material perturbation formula in the cavity is derived, which leads to the theory formula of determining the permittivity and the conductivity. Deposition method is captured to prepare the oxide graphene film based on silicon, then anneal the sample at different temperature. Based on graphical interface software LabVIEW, two test mode control system of the near-field scanning microwave microscope are developed. Finally a electromagnetic model of tip-sample is studied based on the method of FEA(Finite Element Analysis). When the probe moving toward the sample, the change of the electronic filed as well as the property of different material is detected.In this paper, a coaxial resonator with a probe of ah/4 of near-field scanning microwave microscope system, which has the property of high sensitivity and high spatial resolution in the vicinity of the probe, non-destructively and high-efficient measure the high frequency electromagnetic property of the micro-nanostructure materials, by using the electromagnetic change when the probe moving toward the sample.